Heretofore, the method for producing vulcanized tires required a material to separate and release the tire production machinery from the tire carcass during vulcanization. Heretofore, tire production included movement of the uncured tire carcasses to a painting booth where a release material was sprayed on the interior of each tire carcass prior to be introduced to the tire production machinery. This machine, typically a conventional McNeil Corporation Bag-O-Matic, or NRM tire press machine, then vulcanized the tire under heat and pressure, whereby the air bladder expands to compress the carcass into the mold.
The interior of each uncured tire carcass was sprayed prior to its introduction into the tire production machinery. Without such material sprayed on the interior of the uncured tire carcass, upon heat and pressure, the tire carcass would crosslink and polymerize to the expandable air bladder of the machinery. The material sprayed on the interior of the uncured tire carcasses typically included glycol lubricants, silicone oil lubricants, mica or talc, and other chemicals known to those skilled in the art, for providing a releasable lubrication to the interior of the tire carcass, such as described in U.S. Pat. Nos. 4,039,143; 3,713,851; 3,531,624; 3,872,038; 3,905,823; 4,043,924; and 4,066,660. Conventional inside tire release fluids having solids are commercially available from many sources, including for example Harwick Chemical Company, C. P. Hall Company, General Electric Company, and Stauffer Chemical Company.
The inside tire release compositions require the use of solid material, such as mica or talc, to permit the interface between the uncured tire and the air bladder to bleed air as the air bladder expands. Without air bleeding, the tire cured with trapped pockets of air is defective. The solid materials dispersed in the release composition are not capable of withstanding repeated expansion and contraction of the air bladder. Therefore, the art has utilized an application of the composition having these solids to each uncured tire interior rather than a lasting application to the air bladder exterior.
Silicone compositions are frequently employed as release materials or films in a wide variety of applications. Treatment of leather, paper, metals, ceramics and other non-expanding surfaces are disclosed in U.S. Pat. Nos. 3,832,203; 3,674,484; 3,418,162; 3,849,359; 3,436,251; 3,941,856; 3,983,265; 3,846,506; 3,595,838; 3,532,766; 3,308,079; 3,524,900; 3,522,202; and 3,542,574. Silicone compositions have been employed for non-expanding molds and castings such as described in U.S. Pat. Nos. 3,723,567 and 3,883,628, but these compositions are not subjected to repetitive expansion and contraction of the mold or casting block. Finally, examples of silicone compositions for rubber or elastomer articles are disclosed in U.S. Pat. Nos. 3,654,985; 3,699,073; and 4,039,583. However, none of the silicone compositions disclosed in the patents listed in this paragraph are applied to the uncured tire interior or the expandable air bladder for tire production.
Because considerable capital and labor is required to spray each individual tire on its interior surfaces, prior to being placed in the tire production machinery, a need exists for a blend to be applied to the air bladder periodically to accomplish comparable release purposes over considerable production periods, using a composition that may withstand repeated expansion and contraction of the air bladder.